Oil tank for rotary piston internal combustion engine with dry sump lubrication

ABSTRACT

An oil tank for a rotary piston internal combustion engine, in particular of trochoidal construction with a dry sump lubrication of the engine and with a metered fresh oil lubrication of the piston running surface within the casing of the housing, which includes a feed and discharge line, a vent line and a filler pipe; a second oil tank storing the oil supply for the fresh oil lubrication is arranged in the oil tank directly below the filler pipe which second tank is in communication with the main oil tank by way of an overflow and has a separate discharge; an inclined drainage wall is arranged above the oil level in the principal oil tank which extends across the oil tank and terminates shortly in front of the second tank; at least one wall of the second tank and/or the drainage wall is provided with hollow spaces which are in communication with the cooling circulation of the internal combustion engine.

tes n 1 [75] Inventor: Heinz Lamm,Esslingen-St.

Bernhardt, Germany 73] Assignee: Daimler-Benz Aktiengesellschatt,

Stuttgart-Unterturkheim, Germany [22] Filed: Jan. 20, 1972 [21] Appl. No.: 219,285

[30] Foreign Application Priority Data Jan. 21, 1971 Germany P 21 02 699.3

[52] [1.8. CI. 123/196 R, 184/623 [51] Int. Cl......; Fflllm 5/00 [58] Field of Search 184/623, 6.27, 106,

184/104 B, 104 A; 123/196 R, 196 AB; 137/574, 590, 576; 55/277 FOREIGN PATENTS OR APPLICATIONS 931,735 7/1963 Great Britain 184/623 Primary Examiner-Manuel A. Antonakas Attorney-Paul M. Craig, Jr. et al.

[57] ARSTRACT An oil tank for a rotary piston internal combustion engine, in particular of trochoidal construction with a dry sump lubrication of the engine and with a metered fresh oil lubrication of the piston running surface within the casing of the housing, which includes a feed and discharge line, a vent line and a filler pipe; a second oil tank storing the oil supply for the fresh oil lubrication is arranged in the oil tank directly below the filler pipe which second tank is in communication with the main oil tank by way of an overflow and has a separate discharge; an inclined drainage wall is arranged above the oil level in the principal oil tank which extends across the oil tank and terminates shortly in front of the second tank; at least one wall of the second tank and/or the drainage wall is provided with hollow spaces which are in communication with the cooling circulation of the internal combustion engine.

16 Claims, Drawing Figures PATENTEO JUL 3 1 1975 SHEEI 2 OF 2 25 l 247 FIG. 3

OllL TANK FUR ROTARY PHSTON ENTERNAL COMBUSTION ENGINEWITH DRY SUMP LUBRHCATHON The present invention relates to an oil tank for a rotary piston internal combustion engine especially of trochoidal construction with a dry sump lubrication of the engine and with metered fresh oil lubrication of the piston running surface in the casing of the housing, which includes a feed line and a discharge line, a vent line and a filler pipe, whereby within the oil tank accommodating the oil supply for the lubricating circulation of the enginea second tank accommodating the oil supply for the dry, sump lubrication is arranged directly below the filler pipe, which second tank is connected by way of an overflow with the oil tank for the engine lubricating circulation and includes a separate discharge, and in which additionally an inclined discharge or drainage wall is provided above the level of the oil supply below the feed line of the oil participtating in the lubricating circulating, which inclined wall extends transversely through the oil tank and terminates closely in front of the second oil tank with as sharp an edge as possible, as disclosed in German Patent Application P 19 16 967.6.

The oil for the lubrication of the engine or drive unit carrying out a circulation has in an advantageous manner brought about heretofore a warming up of the oil for the fresh oil lubrication.

The present invention is concerned with the task, as contrasted to the aforementioned prior patent application, to achieve not only a considerably improved warm-up or a better adaptation of the temperatures of the circulating oil with the fresh oil but therebeyond to achieve also additionally a rapid warm-up of both oils after the starting of the internal combustion engine. Furthermore, a heat equilibrium between the water and oil circulation is to be made possible by the present invention.

The underlying problems are solved according to the present invention in that at least one wall of the second tank and/or the drainage wall includes hollow spaces which are in operative connection with the cooling circulation of the internal combustion engine.

The oil is utilized more strongly in a rotary piston internal combustion engine of the type described above for the piston cooling than in reciprocating piston engines.

The advantage of the arrangement in accordance with the present invention resides in particular in that during winter operation a more rapid overall warm-up of the internal combustion engine (operating temperature) is possible by the cooling water heated up considerably more rapidly by the internal combustion engine.

During winter operation and in case of short distance drives the oil becomes warm only to a slight extent. The piston is undercooled at small loads and does not give off any heat to the mixture. Fuel condensation results as well as a poor combustion which can be compensated for only by a more pronounced enrichment of the mixture. This undercooling of the piston is still further enhanced by an oil cooler which is necessary especially for full load operation. The application of such an oil cooler is costly in manufacture and not always operationally reliable. Such disadvantages are eliminated by the arrangement proposed by the present invention in which the oil cooler is economized.

In a further advantageous embodiment of the present invention, the wall of the second container disposed opposite the drainage wall may be provided below the drainage wall with at least one outwardly directed arched portion which effects that the largest part of the oil leaving the feed line finally flows downwardly along the wall of the tank with a reduced speed and thus an intensive heat exchange is assured.

Accordingly, it is an object of the present invention to provide an oil tank for a rotary piston internal combustion engine with dry sump lubrication which avoids by simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in an oil tank for a rotary piston internal combustion engine which permits the obtainment of a better warm-up of the oil as well as a more favorable adaptation of the temperatures of the circulating oil with fresh oil.

A still further object of the present invention resides in an oil tank of the type described above which enables a heat equialization between the water and oil circulations of the engine, thereby providing favorable operating conditions when the vehicle is driven during cold winter temperatures or over short distances.

Another object of the present invention resides in an oil tank for a rotary piston internal combustion engine which permits a more rapid overall warm-up of the internal combustion engine, especially during winter operation.

Still another object of the present invention resides in an oil tank for a rotary piston internal combustion engine which prevents an undercooling of the piston, especially at smaller loads, thereby precluding fuel condensation and the attendant poorer combustion of the fuel.

A further object of the present invention resides in an oil tank for a rotary piston internal combustion engine which obviates the need for a separate oil cooler.

These and further objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawing, which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein:

FIG. 1 is a longitudinal cross sectional view through an oil tank in accordance with the present invention;

FIG. 2 is a cross sectional view of the oil tank taken along line llll of FIG. 1;

FIG. 3 is a longitudinal cross-sectional view through a modified embodiment of an oil tank in accordance with the present invention; and

FIG. 4 is a somewhat schematic cross-sectional view through a rotary piston internal combustion engine of trochoidal construction with which the fuel tank in accordance with the present invention is used.

Referring now to the drawing, wherein like reference numerals are used throughout the two views to designate like parts, the oil tank illustrated in FIG. 1 and generally designated therein by referance numeral 1 is of rectangular construction and includes several feed and discharge lines distributed along the circumference thereof. A second tank 3 open toward the top is arranged on the inside of the oil tank 1 along a wall 2; the side walls 5, 6 and 7 of the second tank 3 which are inconnection with the space A for the oil supply of the dry sump lubrication, are provided with hollow spaces 8 (FIG. 1). These hollow spaces 8 to be fed with cooling water are connected with the cooling circulation of the internal combustion engine. The space 9 formed by the second tank 3 serves for the storage of the fresh oil which, like the space 4, includes a pipe connection 11 arranged at the bottom wall of the oil tank 1 for a discharge line 12, which is connected with a metering pump, from which fresh oil is fed from the space 9 in metered quantities to the piston running surface within the housing and to the sealing elements of the internal combustion engine. The pipe connection 13 connected to the space 4 is connected byway of a line 14 with the pressure pump supplying the lubricating system in the drive unit of the internal combustion engine.

A discharge or drainage wall 19 which extends at an inclination from the walls 16, 17 and 18 of the oil tank toward the walls 5, 6 and 7 of the second tank 3 is arranged within the space 4 above the oil level the wall 19 terminates shortly in front of the second tank 3 and is possibly provided also with hollow spaces connected with the cooling circulation of the internal combustion engine. A trapezoidally shaped protective wall 21 is secured at the wall 16 above the drainage or dis charge wall 19, which is inclined more strongly than the drainage wall 19 and constructed considerably smaller than the latter.

A feed line 22 is provided between the drainage wall 19 and the protective wall 21, from which leaves the oil participating in the lubrication circulation, runs down in a thin layer along the drainage or discharge wall 19 and flows over a sharp edge 23 of this drainage toward the side walls 5, 6 and 7 and from there flows downwardly. The gas liberated from the oil at the sharp edge 23 enters, after flowing around the protective wall 21, into a vent line 25 arranged in the upper closure wall 24 of the oil tank 1.

The drainage or discharge wall 19 extended closely to the side walls 5, 6 and 7 which are constructed as heat exchanger, assures a favorable contact of the hot oil with the tank 3 whereby several outwardly directed arched portions 26 (ribs or beads) provided at the side walls 5, 6 and 7 below the edge 23 further intensify the heat exchange.

The filler pipe 27 serving for the filling of oil into the tank 3 is disposed directly above the tank 3 in the upper closure wall 24. The fresh oil reaching the space 9 by way of the tiller pipe 27 fills the tank 1 whereby that oil quantity which the tank 9 cannot store any more, flows over into the space 4 by way of the overflow 28.

Since the cooling water becomes hot much more rapidly after the starting of the internal combustion engine than the circulating oil and the fresh oil, the heat exchanger constituted by the side walls 5, 6 and 7 and the drainage wall 19, serves at first as heater means for the two oils. As a result of the rapid warm-up of the fresh oil a more uniform feed and distribution by the metering pump is obtained.

Furthermore, as a result of the more rapid attainment of the operating temperature of the internal combustion engine, a condensate formation of fuel at the piston, casing and lateral housing is reduced and a more pronounced oil thinning is prevented.

On the other hand, the advantage also exists with the present invention that the oils which have become excessively hot during the operation of the internal combustion are cooled off by the cooling water in such a manner that the fresh oil can hardly exceed a temperature of 90C.

Possibly the space 9 should be so constructed that it no longer comes into contact with the bottom wall 10 but instead is provided in its lower portion with a bottom wall 29 of its own, shown in FIG. 1 in dash line, which like the side walls 5, 6 and 7 is circumcirculated by the oil present within the space 4 forming the main oil tank.

FIG. 3 illustrates such a modified embodiment of an oil tank in accordance with the present invention in which the space 9 no longer comes in contact with the bottom wall 10. The embodiment of FIG. 3 is substantially similar to that of FIG. 1 and like reference numerals are used therefore to designate like parts therein. Differing from FIG. 1, the second tank 3 includes a bottom wall 29 in its lower portion which is spaced from the bottom wall 10 delineating the oil space 4 of the first tank. The connecting pipe 11, which in the embodiment of the oil tank of FIG. 1 is secured at the bottom wall 10, is mounted in the embodiment of FIG. 3 closely above the bottom wall 29 of the second tank 3 at the wall 2 of the tank structure 1. Additionally, a further bottom wall 29', parallel to but spaced underneath the bottom wall 29 is provided in such a manner that the hollow space 8 is continued to extend underneath the second tank 3, with the inlet and outlet arranged as shown in FIG. 2. This provides an even more intensive heat transfer between the coolant in the space 8 and the oil in the tank 3.

The construction of the thus reduced tank 3 is necessary only when the drop from the connecting pipe 11 to the metering pump is inadequate.

FIG. 4 is a somewhat schematic cross-sectional view, taken at right angle to the axis, through a rotary piston internal combustion engine of trochoidal construction of generally conventional design. The housing of the rotary piston internal combustion engine of trochoidal construction, generally designated by reference numeral 30, includes a housing casing 31 provided with a multi-arched running surface 31' and lateral housing parts (not shown) which close off the space 39 on the inside of the housing casing in the lateral directions. A polygonal piston 32 which is arranged on the inside of the space 39 defined by the running surface 31 is rotatably mounted on the eccentric 33 of an eccentric shaft 34 suitably supported in the lateral parts of the housing in a conventional manner, not shown for sake of simplicity. The piston 32 slides with its comers accommodating radial sealing bars 35 along the running surface 31 to provide the various phases of the operation of the internal combustion engine. The housing casing 31 is also provided with an inlet channel 36 and an exhaust channel 37 and also accommodates an ignition device 38. Additionally, in case of injection of the fuel, suitably injection means may also be mounted in the housing casing or lateral parts. Since the operation of a rotary piston internal combustion engine as shown in FIG. 4 is known as such, a detailed description thereof is dispensed with herein.

In order to render the heat exchange more intensive, the walls of the oil tank 1 of FIGS. 1 and 3 may be provided with hollow spaces for the cooling water, as illustrated also in connection with the bottom wall 29 of the tank 3 of the embodiment of FIG. 3.

While I have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

What I claim is:

I. An oil tank for a rotary piston internal combustion engine which includes supply and discharge line means, a vent line, and a filler pipe, and in which a second oil tank storing the supply for a fresh oil lubrication is arranged directly below the filler pipe within the main oil tank for the lubricating circulation of the engine, said second oil tank being in communication with the main oil tank by way of an overflow means and including a separate discharge means, and in which an inclined drainage wall means is provided above the level of the oil supply in the main oil tank and below the supply line means of the oil participating in the oil circulation, said drainage wall means extending transversely through the main oil tank and terminating shortly in front of the second tank, characterized. in that at least one wall means of the two parts consisting of wall means of the second tank and the drainage wall means is provided with a hollow space which is adapted to be operatively connected with a cooling circulation means of the internal combustion engine.

2. An oil tank structure according to claim 1, characterized in that the drainage wall means terminates in front of the second tank with a sharp edge.

3. An oil tank structure according to claim 1, characterized in that the rotary piston engine is of trochoidal construction and includes a dry sump lubrication of the drive unit connected with the main tank and a metered fresh oil lubrication of its piston running surface within its housing casing connected to said second tank.

4. An oil tank structure according to claim ll, characterized in that the wall means of the second tank disposed opposite the drainage wall means is provided below the drainage wall means with at least one outwardly directed arched portion to enhance the heat exchange.

5. An oil tank structure according to claim 4, characterized by a protective wall means above the supply line means, which is considerably shorter than the drainage wall means and extends with a stronger inclination than the drainage wall means.

6. An oil tank structure according to claim 5, characterized in that the vent line is arranged above the protective wall means.

7. An oil tank structure according to claim 6, characterized in that the wall means of the second tank as well as the drainage wall means are provided with hollow spaces in communication with the cooling circulation means.

8. An oil tank structure according to claim 7, characterized in that the oil tank includes a bottom wall and in that the second tank is provided with a.bottom wall spaced from the bottom wall of the oil tank.

9. An oil tank structure according to claim 8, characterized in that the bottom wall of the second tank is also provided with a hollow space in communication with the cooling circulation means.

10. An oil tank structure according to claim 9, characterized in that the drainage wall means terminates in front of the second tank with a sharp edge.

11. An oil tank structure according to claim 10, characterized in that the rotary piston engine is of trochoidal construction and includes a dry sump lubrication of the drive unit connected with the main tank and a metered fresh oil lubrication of its piston running surface within its housing casing connected to said second tank.

12. An oil tank structure according to claim 1, characterized by a protective wall means above the supply line means, which is considerably shorter than the drainage wall means and extends with a stronger inclination than the drainage wall means.

113. An oil tank structure according to claim 12, characterized in that the vent line is arranged above the protective wall means.

M. An oil tank structure according to claim 1, characterized in that the wall means of the second tank as well as the drainage wall means are provided with hollow spaces in communication with the cooling circulation means.

15. An oil tank structure according to claim ll, characterized in that the oil tank includes a bottom wall and in that the second tank is provided with a bottom wall spaced from the bottom wall of the oil tank.

16. An oil tank structure according to claim 15, characterized in that the bottom wall of the second tank is also provided with a hollow space in communication with the cooling circulation means.

I? i W a: i 

1. An oil tank for a rotary piston internal combustion engine which includes supply and discharge line means, a vent line, and a filler pipe, and in which a second oil tank storing the supply for a fresh oil lubrication is arranged directly below the filler pipe within the main oil tank for the lubricating circulation of the engine, said second oil tank being in communication with the main oil tank by way of an overflow means and including a separate discharge means, and in which an inclined drainage wall means is provided above the level of the oil supply in the main oil tank and below the supply line means of the oil participating in the oil circulation, said drainage wall means extending transversely through the main oil tank and terminating shortly in front of the second tank, characterized in that at least one wall means of the two parts consisting of wall means of the second tank and the drainage wall means is provided with a hollow space which is adapted to be operatively connected with a cooling circulation means of the internal combustion engine.
 2. An oil tank structure according to claim 1, characterized in that the drainage wall means terminates in front of the second tank with a sharp edge.
 3. An oil tank structure according to claim 1, characterized in that the rotary piston engine is of trochoidal construction and includes a dry sump lubrication of the drive unit connected with the main tank and a metered fresh oil lubrication of its piston running surface within its housing casing connected to said second tank.
 4. An oil tank structure according to claim 1, characterized in that the wall means of the second tank disposed opposite the drainage wall means is provided below the drainage wall means with at least one outwardly directed arched portion to enhance the heat exchange.
 5. An oil tank structure according to claim 4, characterized by a protective wall means above the supply line means, which is considerably shorter than the drainage wall means and extends with a stronger inclination than the drainage wall means.
 6. An oil tank structure according to claim 5, characterized in that the vent line is arranged above the protective wall means.
 7. An oil tank structure according to claim 6, characterized in that the wall means of the second tank as well as the drainage wall means are provided with hollow spaces in communication with the cooling circulation means.
 8. An oil tank structure according to claim 7, characterized in that the oil tank includes a bottom wall and in that the second tank is provided with a bottom wall spaced from the bottom wall of the oil tank.
 9. An oil tank structure according to claim 8, characterized in that the bottom wall of the second tank is also provided with a hollow space in communication with the cooling circulation means.
 10. An oil tank structure according to claim 9, characterized in that the drainage wall means terminates in front of the second tank with a sharp edge.
 11. An oil tank structure according to claim 10, characterized in that the rotary piston engine is of trochoidal construction and includes a dry sump lubrication of the drive unit connected with the main tank and a metered fresh oil lubrication of its piston running surface within its housing casing connected to said second tank.
 12. An oil tank structure according to claim 1, characterized by a protective wall means above the supply line means, which is considerably shorter than the drainage wall means and extends with a stronger inclination than the drainage wall means.
 13. An oil tank structure according to claim 12, characterized in that the vent line is arranged above the protective wall means.
 14. An oil tank structure according to claim 1, characterized in that the wall means of the second tank as well as the drainage wall means are provided with hollow spaces in communication with the cooling circulation means.
 15. An oil tank structure according to claim 1, characterized in that the oil tank includes a bottom wall and in that the second tank is provided with a bottom wall spaced from the bottom wall of the oil tank.
 16. An oil tank structure according to claim 15, characterized in that the bottom wall of the second tank is also provided with a hollow space in communication with the cooling circulation means. 